Viewing and Understanding Email Internet Transport Headers in .EML Files

A screen shot of Pst Viewer Pro displaying email internet header info.


An EML (Electronic Mail) file is an open file format used to store individual email messages. It is a standard file format often associated with email clients like Thunderbird that follow the MIME (Multipurpose Internet Mail Extensions) standard. EML files contain the complete content of an email message, including the text, attachments, and metadata.

An email internet transport header, also known as an email header or message header, is a block of metadata information that provides details about the origin, route, and content of an email message. This information is not typically visible in the body of the email when you read it but can be viewed by accessing the email’s header section.

Email internet headers are usually not visible to users. A useful tool for managing EML files and viewing the internet header is a Pst Viewer Pro (formerly known as EML Viewer Pro) by Encryptomatic LLC, a U.S. based software developer.

Here are some key components typically found in an email internet header:

  1. Return-Path:
  • The email address to which bounce notifications and delivery errors are sent.
  1. Received:
  • This section contains information about the servers through which the email passed on its way to the recipient. It includes details like the server’s IP address, timestamp, and authentication information.
  1. From:
  • The email address of the sender.
  1. To:
  • The email address of the recipient.
  1. Subject:
  • The subject line of the email.
  1. Date:
  • The timestamp indicating when the email was sent.
  1. Message-ID:
  • A unique identifier assigned to the email for tracking and reference purposes.
  1. MIME-Version:
  • The version of the Multipurpose Internet Mail Extensions (MIME) standard used in the email. MIME is a standard that extends the format of email messages to support text in character sets other than ASCII, as well as attachments of audio, video, images, and application programs.
  1. Content-Type:
  • Specifies the type of content contained in the email, such as text, HTML, or attachments.
  1. X-Headers:
    • Additional custom headers that may be added by email servers or applications for specific purposes.

The email header is crucial for various reasons, including:

  • Routing Information: It shows the servers and paths the email took to reach its destination.
  • Authentication: Some headers provide information on email authentication methods used, helping to verify the legitimacy of the sender.
  • Spam Filtering: Email headers can contain information used by spam filters to assess the likelihood that an email is spam.
  • Troubleshooting: When dealing with email delivery issues, the header can be analyzed to identify potential problems in the routing process.

To view the email header in most email clients, you can look for an option like “View Source,” “Show Original,” or “View Message Source.” Analyzing email headers can be useful in understanding the journey of an email and in troubleshooting email-related problems.

Get a free 15 day trial of Pst Viewer Pro for Windows 11/10.

Introducing MailDex for Email Discovery

The main viewing pane of MailDex email viewer/discovery software for Windows.

MailDex Makes Email Discovery Affordable for Legal Professionals

Email remains a vital form of communication in the legal and business worlds. It is used to exchange information, documents, and can be an important source of evidence. However, email can also be a source of legal problems. If you are involved in a legal case, you may need to produce your email records as evidence. This can be an expensive and daunting task, especially if you have a large volume of emails to review.

MailDex software box illustration.

MailDex by Encryptomatic LLC is a Windows software tool often used in email discovery. MailDex can help you quickly and easily produce the emails you need for legal discovery and your defense. MailDex is compatible with a wide range of email formats, including EML, PST, OST, MBOX, and MSG. It also supports a variety of advanced search features, so you can find the emails you need quickly and easily. Before outsourcing to an expensive discovery firm, a first pass using affordable MailDex may produce the documents you need at a fraction of the cost.

MailDex is a complete system for managing, viewing, searching and converting email content. Many of the functions can be customized by the user to achieve specific goals and results. Here are some of the key features of MailDex:

  • Compatible with a wide range of email formats: MailDex can read and index emails from a wide range of email clients, including Microsoft Outlook, Apple Mail, and Gmail.
  • Advanced search features: MailDex supports a variety of advanced search features, such as keyword search, date range search, and sender/recipient search.
  • Easy to use: MailDex is easy to use, even for non-technical users. The interface is intuitive and straightforward, and there are plenty of help resources available.
  • Affordable: MailDex is an affordable option for legal discovery. There is a 15 day free trial available, and the pricing is very competitive.

If you are a legal professional who needs to find emails for legal discovery, MailDex may be the perfect tool for you. It is easy to use, affordable, and compatible with a wide range of email formats.

Here are some additional benefits of using MailDex for legal discovery:

  • It can help you save time and money. MailDex can help you quickly and easily find the emails you need, so you don’t have to spend hours manually searching through your inbox.
  • It can help you improve your efficiency. MailDex can help you automate many of the tasks involved in legal discovery, such as indexing, searching, and exporting.
  • It can help you reduce your risk of error. MailDex is a powerful tool that can help you avoid making mistakes during the legal discovery process.

If you are looking for a reliable and affordable email discovery tool, try MailDex today and see how it can save you time and money with your email discovery needs.